|Publication number||US8107178 B2|
|Application number||US 11/901,544|
|Publication date||Jan 31, 2012|
|Filing date||Sep 18, 2007|
|Priority date||Dec 26, 2006|
|Also published as||US20080151435|
|Publication number||11901544, 901544, US 8107178 B2, US 8107178B2, US-B2-8107178, US8107178 B2, US8107178B2|
|Original Assignee||Toshiba Storage Device Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (23), Classifications (9), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates to a storage apparatus, a method of detecting a failure in a head of a storage apparatus, and a storage medium storing a failure detection program. And more particularly, to a storage apparatus which is provided with a tunnel effect MR head (TuMR head) as a head to thereby read information from a recording medium such as a magnetic disk, a method of detecting a failure in a head of a storage apparatus, and a storage medium storing a failure detection program.
2. Description of the Related Technology
In a storage apparatus, (for example, an HDD that has recently been used in various types of products such as a desktop PC, notebook PC, server, audio-visual equipment, and automobile product), linear density (BPI)/transfer rate is improved along with improvement in the recording density (surface density). In recent years, various types of magnetic disk heads supporting a higher transfer rate are developed in order to allow the technological update of the storage apparatus and produced on a commercial basis.
As one of the above magnetic disk heads, there is known a TuMR head which is based on tunnel effect (refer to, e.g., Patent Document 1 (Patent Publication WO2002/093564)). A magnetic recording/reproducing apparatus disclosed in this Patent Document 1 has a TuMR head serving as a magnetic reproducing head and a signal processing circuit for supplying a signal detection current and voltage to the TuMR head and amplifying and processing a signal obtained from the TuMR head. In this magnetic recording/reproducing apparatus, when the SNR of a detection signal processed in the signal processing circuit exhibits the maximum value within a predetermined range of voltages applied to the TuMR head, the TuMR head is driven by a voltage drive circuit; otherwise, the TuMR head is driven by a current drive circuit. The TuMR head is used as a mainstream reading head for a magnetic recording/reproducing apparatus regardless of whether the magnetic recording/reproducing apparatus adopts a horizontal recording mode or vertical recording mode.
However, the TuMR head is still in the early days of its development and therefore has a problem concerning long-term reliability throughout product life under today's situation that quality verification time must be shortened.
The present invention has been made to solve the above problem, and an object thereof is to provide a storage apparatus, a method of detecting a failure in a head, and a failure detection program capable of ensuring long-term reliability of a storage apparatus using, e.g., a TuMR head as a reading head.
To solve the above problem, according to a first aspect of the present invention, there is provided a storage apparatus comprising: a read section that receives a predetermined electrical parameter to read out data from a recording medium; a characteristic detection part that detects a plurality of characteristic values which are predetermined indicators of the read section corresponding to the plurality of different predetermined electrical parameters that have been given to the read part; a characteristic relation acquisition part that acquires as a characteristic relation a relationship between the predetermined electrical parameter and characteristic value from the predetermined electrical parameter and plurality of characteristic values acquired by the characteristic detection part; and a determination section that determines presence/absence of failure in the read part based on the characteristic relation acquired by the characteristic relation acquisition part.
In the storage apparatus according to the present invention, the characteristic detection part detects the characteristic value in a temporal manner as well as the characteristic relation acquisition part acquires the characteristic relation in a temporal manner based on the characteristic value that has been detected in a temporal manner, and the characteristic relation acquisition part determines presence/absence of failure in the read part based on a temporal change in the characteristic relation.
In the storage apparatus according to the present invention, the characteristic relation is a slope of the characteristic value corresponding to the predetermined electrical parameters obtained at a plurality of measurement points.
Further, according to a second aspect of the present invention, there is provided a method of detecting a failure in a head of a storage apparatus, comprising: a read step that gives a plurality of different predetermined electrical parameters to a head to read out data from a recording medium using the head; a characteristic detection step that detects a characteristic value which is a predetermined indicator of the head corresponding to the predetermined electrical parameter that has been given in the read step; a characteristic relation acquisition step that acquires as a characteristic relation a relationship between the predetermined electrical parameter and characteristic value from the predetermined electrical parameter and plurality of characteristic values acquired by the characteristic detection step; and a determination step that determines presence/absence of failure in the head based on the characteristic relation acquired by the characteristic relation acquisition step.
Further, according to a third aspect of the present invention, there is provided a storage medium storing a failure detection program that allows a computer to execute a method of detecting a failure in a head of a storage apparatus, the program allowing the computer to execute: a read step that gives a plurality of different predetermined electrical parameters to a head to read out data from a recording medium using the head; a characteristic detection step that detects a characteristic value which is a predetermined indicator of the head corresponding to the predetermined electrical parameter that has been given in the read step; a characteristic relation acquisition step that acquires as a characteristic relation a relationship between the predetermined electrical parameter and characteristic value from the predetermined electrical parameter and plurality of characteristic values acquired by the characteristic detection step; and a determination step that determines presence/absence of failure in the head based on the characteristic relation acquired by the characteristic relation acquisition step.
According to the present invention, there can be provided a storage apparatus, a method of detecting a failure in a head of a storage apparatus, and a storage medium storing a failure detection program capable of ensuring long-term reliability.
An embodiment of the present invention will be described below, taking a magnetic disk drive as an example of a storage apparatus.
The HDD 1 has, on the side of a disk enclosure 9, a preamplifier 10 which is a fixed amplifier that performs write operation for a head and read operation from the head. The number of channels provided in the preamplifier 10 corresponds to the number (N) of heads.
The preamplifier 10 includes a write driver 11, a heater driver 12, a read preamplifier 13 and a control circuit 14 therefor.
Further, the HDD 1 has an VCM (Voice Coil Motor) 15 that controls operation of an actuator supporting a head, an SPM (Spindle Motor) 17 that controls rotation of a spindle shaft holding a magnetic disk 16 which is a recording medium to which data is written for storage, and a dual head 18 having a write head for data write and an MR head for data read. The HDD 1 in the embodiment corresponds to a storage apparatus of the present invention. The head in the present embodiment corresponds to a read part of the present invention. A characteristic detection section, a characteristic relation acquisition section, and a determination section are each constituted by the head 18, preamplifier 10, RAM 4, ROM 5, and MCU 6.
The HDD according to the embodiment of the present invention makes a determination of the occurrence of head (TuMR) failure for itself. That is, in the case where a given characteristic relation exceeds a threshold value (predetermined range) before product shipment, or in the case where the characteristic relation fluctuates with time, the HDD determines that the HDD itself do not meet product shipment criterion and thereby removed from a shipment list during a test process.
The above test process may be performed at any stage (e.g., in an assembled state of a head suspension, after the head suspension assembly has been fitted to an actuator arm, or the like) of the assembly process of the storage apparatus.
Therefore, it is possible to remove a faulty head before the assembly of the storage apparatus has been completed. Thus, selection of a sophisticated head can be made with the result that only the selected sophisticated head is mounted on the storage apparatus, enabling the storage apparatus to be a product of high performance and excellent reliability.
Further, the HDD according to the present embodiment performs periodic monitoring for itself after product shipment. That is, in the case where a given characteristic relation exceeds a threshold value (predetermined range), or in the case where the characteristic relation fluctuates with time (temporally changes), the HDD generates an alarm to notify a user of the occurrence of failure and thereby reliability of the TuMR, which is a write head, is always ensured.
Therefore, it is possible to notify the user of failure in the head before the storage apparatus cannot normally perform its recording/reproducing operation. Thus, the user can make adequate responses such as repair and data backup, enabling improvement in reliability of the storage apparatus.
In the periodic monitoring performed after product shipment, power-on count (the number of times of power-on operations) or access count is recorded as a history. The monitoring is performed every time the power-on count or access count reaches a predetermined count and thereby the temporal change can be determined.
Operation of the present embodiment will be described as follows.
In general, a head IC (Pre Amp) that controls a head of a magnetic disk drive has a monitor circuit represented by the following equation (1). The monitor circuit is used for measuring the head resistance value Rmr.
(A is fixed gain)
In the case where a given constant bias voltage is applied, a relationship between the monitor voltage BHV and head resistance value Rmr as shown in
The following equation (2) is an inverse operation of the equation (1).
Rmr=A* (Vb/BHV) (2)
In the case where the head resistance value Rmr assumes 350 [ω] in
In the present embodiment, the above relationships are used to obtain a relationship (characteristic relation or correlation) between the head resistance value (characteristic value) and bias voltage (electrical parameter). Then, a slope representing the relationship between the head resistance and bias voltage or a temporal change in the slope is detected to thereby determine presence/absence of failure. When it is determined that failure has occurred, the failure detection alarm is generated.
The head resistance value keeps constant unless degradation of the head element occurs. However, in some heads, the resistance value thereof changes depending on frequency of use. In order to cope with this, the monitor voltage BHV is monitored to thereby capture a temporal change in the head resistance value, and determination is made as follows: when a change rate of the head resistance value falls within a given standard value range, the head is determined to be normal, while when the change rate falls outside the standard value range, the head is determined to be abnormal and the failure detection alarm is generated. This can increase reliability in the failure detection as compared to the case where the occurrence of failure is determined only by detecting the slope.
A failure detection means using the temporal change monitors the initial state during the product shipment process to acquire a relationship (characteristic relation) between the head resistance value (characteristic value) and bias voltage and further measures (periodically) the slope once again after the pre-shipment test is conducted. In this manner, a change in the slope is detected before product shipment to thereby detect degradation of the head element, if it occurs.
Thus, as shown in
The example of
Further, in the field operation after product shipment, the periodic monitoring is allowed to be automatically performed for alarm notification to the user.
A concrete example of above operation will be described using flowcharts Of
After a product pre-shipment test is started (step S1) to turn the power ON (step S2), a predetermined test is carried out (step S3) and, after that, the operation according to the present embodiment is started appropriately (step S4). First, a plurality of voltage values (points) are set for the bias voltage to be measured (step S5). The VTM (characteristic value) which corresponds to the head resistance value is measured at the set points (step S6), and slope Ax is obtained from the VTM values at the respective points (step S7). Then, the slope is set as an initial value and stored in a memory (step S8), and it is determined whether the slope falls within a standard value range (in other words, whether the slope exceeds a predetermined threshold value) (step S9). In the case where it is determined that the slope does not fall within the standard value range (N in step S9), it is determined that failure (defect) has occurred and the failure detection alarm is generated (step S15). In the case where it is determined that the slope falls within the standard value range (Y in step S9), it is determined that no failure has occurred.
Then, after test items other than those according to the present embodiment are carried out (step S10), the VTM is measured once again at the respective points set in step S5 (step S11), and the slope Δx is obtained in the similar manner as step S7 (step S12). Then, a difference between the slope obtained in step S12 and that obtained in step S7 is obtained and, then, whether the difference falls within a predetermined standard value range is determined. In the case where it is determined that the difference does not fall within the standard value range (in other words, in the case where it is determined that the difference exceeds the standard value range) (N in step S13), it is determined that failure (defect) has occurred and the failure detection alarm is generated (step S16). In the case where it is determined that the difference does not exceed the standard value range (Y in step S13), it is determined that no failure has occurred, and this flow is ended (step S14).
In the case where a plurality of heads are provided, the same failure determination processing is performed for respective heads.
Next, failure determination processing performed after product shipment will be described.
After power is turned ON to activate system operation (step S21), access processing is made to the HDD (step S22). Then, it is determined whether command reception processing is being performed (step S23) and, in the case where it is determined that the command reception processing is not being performed (in other words, the HDD is in its idle time) (N in step S23), TuMR head failure determination processing is started (step S24).
Alternatively, a configuration may be adopted in which power-on count or access count is stored as a history and TuMR head failure determination processing is started during the idle time at the timing at which the power-on count or access count exceeds a predetermined count (for example, when the power-on count reaches 100 or 1000).
The VTM is measured at the respective points set in step 5 of
As described above, the initial characteristic of the TuMR head is measured and, after a given time period has elapsed, the characteristic thereof is measured once again. In the case where the initial characteristic has been changed by a degree exceeding a given allowance, it is possible to recognize that the sensitivity of the head is changed.
In such a case, it can be determined that any failure has occurred in the characteristic of the head and, accordingly, it can be considered that there is a problem in reliability of the head. Therefore, it seems unlikely that the head whose sensitivity characteristic has been changed will be workable, so that the relevant head is determined to be treated as a defective one.
Further, even after product shipment, the failure detection alarm is generated if failure has occurred. This enables early replacement of the defective head. As described above, action on the head whose characteristic has been changed can be taken before product shipment, as well as, the characteristic change can be detected at an early stage even after product shipment, thereby providing a magnetic disk drive having high reliability.
Although a magnetic disk drive is used in the above embodiment, it goes without saying that the present invention is also applicable to a disk drive other than the magnetic disk drive, such as a flexible disk drive or magneto-optical disk drive.
Further, when a program that allows a computer to execute the above operation steps shown in the flowcharts of the embodiment, a failure detection program of the present invention can be provided. By storing this failure detection program in a computer-readable storage medium, it is possible to allow the computer to execute the program. The computer mentioned here includes: a host device such as a personal computer, a controller for a test apparatus, and a controller such as MPU or CPU of a storage apparatus. The computer-readable medium mentioned here includes: a portable storage medium such as a CD-ROM, a flexible disk, a DVD disk, a magneto-optical disk, or an IC card; a database that holds computer program; another computer and database thereof; and a transmission medium on a network line.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2913652 *||Dec 31, 1956||Nov 17, 1959||Burroughs Corp||Speed regulating servo system|
|US3497610 *||Sep 26, 1966||Feb 24, 1970||New England Merchants National||Automatic marker production system utilizing electro-optical scanning means|
|US3517308 *||Feb 1, 1968||Jun 23, 1970||Mirdadian Mohammad Kian||Apparatus and method for testing electronic counting systems|
|US5426537 *||Jun 30, 1993||Jun 20, 1995||Ampex Corporation||Method and apparatus for automatically adjusting the overshoot of a record head in response to the record head gap depth|
|US5438470 *||May 13, 1994||Aug 1, 1995||Read-Rite Corporation||Magnetoresistive structure with contiguous junction hard bias design with low lead resistance|
|US5739706 *||Feb 28, 1997||Apr 14, 1998||Rohm Co., Ltd.||Magnetically recording apparatus|
|US5751510 *||Jan 2, 1996||May 12, 1998||International Business Machines Corporation||Method and apparatus for restoring a thermal response signal of a magnetoresistive head|
|US6002539 *||Jun 10, 1998||Dec 14, 1999||International Business Machines Corporation||Method for calibrating a dual element magnetoresistive head|
|US6088176 *||Jan 2, 1996||Jul 11, 2000||International Business Machines Corporation||Method and apparatus for separating magnetic and thermal components from an MR read signal|
|US6150809 *||Sep 18, 1997||Nov 21, 2000||Tpl, Inc.||Giant magnetorestive sensors and sensor arrays for detection and imaging of anomalies in conductive materials|
|US6195219 *||Oct 20, 1998||Feb 27, 2001||International Business Machines Corporation||Method and apparatus for improving a thermal response of a magnetoresistive element|
|US6246553 *||Dec 2, 1998||Jun 12, 2001||International Business Machines Corporation||Shielded magnetoresistive head with charge clamp|
|US6384994 *||Feb 1, 2000||May 7, 2002||International Business Machines Corporation||Method for positioning a magnetoresistive head using a thermal response to servo information on the record medium|
|US6657830 *||Jul 25, 2001||Dec 2, 2003||Hitachi, Ltd.||Magnetoresistive magnetic sensor with tunnel effect and magnetic storage apparatus|
|US6831807 *||Nov 5, 2002||Dec 14, 2004||Matsushita Electric Industrial Co., Ltd.||Head positioner and disk drive using the same|
|US6917499 *||Oct 3, 2003||Jul 12, 2005||Hitachi, Ltd.||Magnetoresistive magnetic sensor and magnetic storage apparatus|
|US7062698||Sep 4, 2002||Jun 13, 2006||Samsung Electronics Co., Ltd.||Method and apparatus to control head instability in a data storage system|
|US7119990 *||Feb 3, 2003||Oct 10, 2006||Komag, Inc.||Storage device including a center tapped write transducer|
|US7268965 *||Jul 9, 2004||Sep 11, 2007||Hitachi Global Storage Technologies Netherlands B.V.||Method of manufacturing an apparatus and a method for estimating the flyheight of an airbearing slider in a storage device|
|US20020181135 *||Oct 23, 2001||Dec 5, 2002||Mitsubishi Denki Kabushiki Kaisha||Current bias circuit used in magnetic-signal detection head|
|US20070230008 *||Jan 26, 2007||Oct 4, 2007||Hitachi, Ltd.||Reproducing circuit and a magnetic disk apparatus using same|
|JP2003178402A||Title not available|
|WO2002093564A1||May 16, 2001||Nov 21, 2002||Hitachi Ltd||Method for driving magnetic reproducing head, and magnetic recording/reproducing apparatus|
|Cooperative Classification||G11B5/455, G11B27/36, G11B5/09, G11B2220/2516|
|European Classification||G11B27/36, G11B5/09, G11B5/455|
|Sep 18, 2007||AS||Assignment|
Owner name: FUJITSU LIMITED, JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TAKAHASHI, TSUYOSHI;REEL/FRAME:019884/0129
Effective date: 20070606
|Nov 23, 2009||AS||Assignment|
Owner name: TOSHIBA STORAGE DEVICE CORPORATION,JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:FUJITSU LIMITED;REEL/FRAME:023558/0225
Effective date: 20091014
|Feb 8, 2012||AS||Assignment|
Owner name: KABUSHIKI KAISHA TOSHIBA, JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOSHIBA STORAGE DEVICE CORPORATION;REEL/FRAME:027674/0653
Effective date: 20120125
|Sep 11, 2015||REMI||Maintenance fee reminder mailed|